We propose to study the relationship between population density and human behavior in a large urban area--Chicago. The study will examine the relationships between varying levels of density and a number of rates of "pathological" behavior at the ecological or areal level, and try to establish the relative importance of density as an explanatory variable when compared to other more traditional sociological variables such as race and social class. The study will then proceed from these ecological findings to a detailed analysis of individual households, through the use of a structured interview, administered to a representative sample of persons stratified by density, social class, and levels of "pathological" behavior, such as morbidity, fertility, ineffectual child care, antisocial behavior, and psychiatric disorder. Our goal is to not only establish whether there is a relationship between high density and specific types of behavior, but to also try to determine how these relationships obtain (i.e., what are the behavioral and other linkages involved in this relationship).